1. Field of the Invention
The present invention relates generally to a supporting structure, incorporated in a lens barrel, for supporting a rotatable ring therein so that rotatable ring can rotate about its rotational axis while moving along the rotational axis, and more particularly, to a mechanism for removing backlash in the rotatable ring.
2. Description of the Related Art
Although providing relatively sliding portions of moving parts with some play (backlash) therebetween is essential, various backlash removing mechanisms have been proposed because backlash becomes a leading cause of deteriorating accuracy in moving such moving parts. For instance, retractable photographing (imaging) lenses in which a rotatable ring (such as a cam ring for moving a lens group along an optical axis) rotates while advancing from a fully retracted position toward a ready-to-photograph position in a photographing range (e.g., zooming range of zoom lens) upon power being turned ON are known in the art. In such known retractable photographing lenses, a mechanism for removing backlash and play in the rotatable ring is generally complicated.